Lexus ES: Lost Communication with Wiper System LIN BUS (B1373)

DESCRIPTION

The main body ECU (multiplex network body ECU) and windshield wiper motor assembly communicate via LIN communication. The main body ECU (multiplex network body ECU) stores this DTC if communication becomes abnormal.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory	DTC Output from
B1373	Lost Communication with Wiper System LIN BUS	Auxiliary battery voltage is 9.5 V or more A malfunction in the communication or LIN communication line between the main body ECU (multiplex network body ECU) and components of the wiper system occurs 7 seconds or more 3 times consecutively	Windshield wiper motor assembly Main body ECU (multiplex network body ECU) Harness or connector Rain sensor*	○	Main Body

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

Click here

PROCEDURE

1.	CONFIRM MODEL

(a) Choose the model to be inspected.

Result	Proceed to
w/o Auto Wiper System	A
w/ Auto Wiper System	B

B

GO TO STEP 4

A

2.	CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - WINDSHIELD WIPER MOTOR ASSEMBLY)

(a) Disconnect the G36 main body ECU (multiplex network body ECU) connector.

(b) Disconnect the A38 windshield wiper motor assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G36-3 (LIN3) or A38-2 (LIN) - Body ground	Always	10 kΩ Higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.	CHECK MAIN BODY ECU

*a	Component without harness connected (Main Body ECU (Multiplex Network Body ECU)

(a) Check for voltage and pulses according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
G36-3 (LIN3) - Body ground	Power switch off	Below 1 V
	Power switch on (IG)	Pulse generation

OK

REPLACE WINDSHIELD WIPER MOTOR ASSEMBLY

NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

4.	CHECK RAIN SENSOR

(a) Disconnect the P2 rain sensor connector.

(b) Clear the DTCs.

Body Electrical > Main Body > Clear DTCs

(c) Turn the power switch on (IG) and wait for at least 10 seconds.

(d) Check for DTCs.

Body Electrical > Main Body > Trouble Codes

Result	Proceed to
Only DTC B1279 is output	A
DTC B1373 is output	B

A

REPLACE RAIN SENSOR

B

5.	CHECK WINDSHIELD WIPER MOTOR ASSEMBLY

(a) Disconnect the A38 windshield wiper motor assembly connector.

(b) Clear the DTCs.

Body Electrical > Main Body > Clear DTCs

(c) Turn the power switch on (IG) and wait for at least 10 seconds.

(d) Check for DTCs.

Body Electrical > Main Body > Trouble Codes

Result	Proceed to
Only DTC B1245 is output	A
DTC B1373 is output	B

A

REPLACE WINDSHIELD WIPER MOTOR ASSEMBLY

B

6.	CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - WINDSHIELD WIPER MOTOR ASSEMBLY AND RAIN SENSOR)

(a) Disconnect the G36 main body ECU (multiplex network body ECU) connector.

(b) Clear the DTCs.

Body Electrical > Main Body > Clear DTCs

(c) Turn the power switch on (IG) and wait for at least 10 seconds.

(d) Check for DTCs.

Body Electrical > Main Body > Trouble Codes

Result	Proceed to
DTC B1373 is not output	A
DTC B1373 is output	B

A

REPAIR OR REPLACE HARNESS OR CONNECTOR

B

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

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